Seat belt not clicking/latching

[catfish93]

My dad borrowed my car and he told me the seat belt broke on him. When you pull the belt across you and go to click it in to the buckle next to the seat, it pushes in but won't click. I noticed the release button is sort of cracked?? Broken?? Like a piece of red plastic broke off and is probably stuck in there. I did get hit in the side last year. Possibly stemming from the wreck? He bucked up by latching it in the passenger seat. Not really very safe. What do I do, and where the heck do I get this part? 89 sidekick 4x4, stock, 53k original miles. I can post a pic if needed.